Animals, such as hogs, require a continuous supply of clean, fresh water. The water is supplied with animal watering systems located in animal confinement areas. In some locations during the winter months the atmospheric temperatures fall well below freezing. The cold temperature causes the watering systems to freeze up. In some watering systems heaters are used in the winter months to prevent the water from freezing. The heaters utilize an outside source of energy such as electricity or fuel oil. Examples of animal watering devices having heater elements to prevent the freezing of the water are disclosed by Peterson et al in U.S. Pat. Nos. 4,078,524 and 4,248,177. Peterson et al in U.S. Pat. No. 4,248,177 discloses an animal waterer having a recirculating water system that utilizes a heater element associated with pipes to provide for the heating and circulation of the heated water. The pipes are connected to valve actuated nipples secured to an upright housing. The watering nipples extend outwardly from the sides of the housing and are exposed to the cold atmospheric air. Shields located adjacent opposite sides of the nipples are used to require the animal to approach the nipples from a frontal position.
Armstrong et al in U.S. Pat. No. 3,949,707 disclose a livestock watering system that utilizes ground heat to minimize the freezing of water in a nipple type watering apparatus. The water is stored in a tank below ground. A pump connected to the tank delivers water via pipes to the watering nipples. The pump continuously operates to circulate the water in the pipes leading to and from the nipples. An outside source of power, such as electricity, is required to operate the motor driving the pump. When the pump is inoperative, water does not circulate to the nipples.